Thread tensioning device for textile machines



Jan. 25, 19:66 F. LEMARCHANDQ 3,231,216

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' ATTORNEY United States Patent 3,231,216 THREAD TENSIONING DEVICE FORTEXTILE MACHINES Francis :LemarchamL Rouen, France, asslgnor to MachinesBourgeas Pain, Valence, Drome, France, a French company Filed Jan. 15,1963, Ser. No. 251,554 Claims priority, application France, Jan. l19,1962, 885,294, Patent 1,319,433 9 Claims. (CI. 242-150) Theinventionrelates to thread-tensioning devices for textile machines such as, forexample, creeis,V reelingmachines, spoolers, winders, false-twistmachines, etc.

In the majority of known thread-tensioning devices, the thread passesover two tension cylinders which are positionally adjustable at theoutset but which remain stationary during the operation of the machine,the thread being guided, at least on the output side of the said tensioncylinders, by means of a roller or like guiding member which issubjected tothe actionof an adjustable counterweight.

In the case of devices of this type, it is difficult to adjust thetension of the'thread during operation of the machine and it is in anycase necessary to carry out this adjustment individually by hand on eachthread-tensioning device, with the result that, in order to adjust allthe thread-tensioning devices of a same machine, a relativelysubstantial amount of time has to be spent.

The purpose of the invention is to construct a threadtensioning devicewhich not only ensures that the thread tension is automaticallyregulated to a constant predetermined value, but also makes it possibleto modify the value of this tension at any desired moment during theoperation of the machine, either by manual control means or by automaticmeans, as a function of time or of a pre-determined programme, forexample in response to the diameter of the bobbins of threadwhich areundergoing formation on the machine, and finally, which makes itpossible to eifect a simultaneous adjustment of all the tensioningdevices of a same machine, star-ting from a single common adjustmentunit.

To this end, in accordance with the invention, the thread tensionregulating device comprises a feeler element with a-roller which iselastcally urged against the thread with a constant pressure which canpreferably be regulated, and a thread tension regulating systemcontrolled by the said feeler element in such manner that, depending onwhether the thread tension tends to increaseV or decrease, the feelerroller is thrust back either in one direction by the thread or in theopposite direction by the elastic means actuating the said feelerelement and produces action on the thread tension regulating system inthe direction of a reduction or increase respectively, so as tocompensate incipient variations in tension.

By virtue of this constructional arrangement, and in view of the factthat the feeler element acts upon the thread tension regulating systemso as to compensate possible variations in tension, it will beunderstood that a very flexible and very effective regulation of tensionis thus obtained and that it is possible to effect a modification of thevalue of the thread tension simply by varying the pressure applied bythe feeler element on the thread.

The invention also has for its object forms of embodiment which compriseat least one of the following characteristic features:

(a) The thread tension regulating system is constituted by two paralleltension cylinders around which the thread passes in an S, the saidcylinders being carried by a support which pivots about a shaft mountedparallel to to the feeler element.

the axes of the tension cylinders and which is coupled hmtif l PatentedJan.,` Z5, w66

(b) The thread tension regulating elements are conn stituted by twodiscs between which the threads pass, the said discs being urged towardseach other by the feeler V t (d) Ther tension cylinders are carried byaA supportl which is adapted to pivot co-axially with the arm whichcarries the two feeler rollers, in the direction opposite Ato the saidarm and preferably in a speed ratio which is greater `than unity,especially'of the order of 2:1.

(e) The coupling between the arm which carries the feeler rollers andthe support which carries the tension cylinder is constituted by twotoothed wheels which are respectively integral with the said arm andwith the said support, the said two toothed wheels being in mesh with acommon intermediate toothed wheel, the shaft of which is stationary.

(f) The arm which carries the feeler rollers and the support whichcarries 'the tension cylinders are connected together by means of acoupling comprising two crankpins which are respectively integral withthe coaxial shafts of the said arm and the said support and which l" arecoupled at two points of an intermediate pivotal lever which are locatedat distances from the fulcrum of this y latter which arerespeetively'proportionali to the angular speeds of the arm and of thesupport. 4

(g) The two discs of the disc-type tensioning device are respectivelycoupled axially to two coaxial shafts which are movable one with respectto the other, both axially and in rotation, one of the said two shaftsbeing designed to carry the pivotal arm which supports the feeler rollerwhilst the other shaft is secured against rotation and a camtransmission produces the relative sliding of the two shafts under theaction of the pivotal motion of that shaft which carries the feelerroller.

(h) The feeler roller is urged against the thread by means of anelectromagnetic device such as, for example, an electric motor of thetype known as a torque-motor.

(i) The electromagnetic device comprises a' pivoting system which issecured to the arm tted with the feeler roller and which carries twopole'pieces adapted to move in front of two stationary pole pieces whichare displaced angularly in such manner that, when the area of the airgapbetween two oppositely facing pole pieces decreases, the area of theair-gap between the two other oppositely facing pole pieces increases,two of the opposite faces having the same polarity whilst the two otheropposite faces have different polarities in order that the torque`provided by the moving system may be substantiallyv constant,irrespective of the angular position thereof.

(j) The circuit supplying current to the electromagneticV device whichapplies the feeler roller against the thread is placed under the controlof a device such as a r eostat which comprises a moving element coupledto a member, the displacements of which are dependent on the value ofthe diameter of the bobbin of thread which is undergoing FIG. .3 is apartial transverse cross-section taken along the line III-III of FIG. l,

FIG. 4 is a transverse cross-section taken along the line IV-IV of FIG.l,

FIG. S'is a plan view which is similar to FIG, 2 and which shows themembers in another position,

FIG. 6 is an axial cross-section of a first variant of the form ofembodiment of FIGS. 1 to 5,

FIG. 7 is an axial cross-section taken along the line VlI-VII of FIG. 6,

FIG. 8 is an axial cross-section of a second variant,

FIG. 9 is a partial transverse cross-section taken along the line IX-IXof FIG. 8,

FIG. 10 is a view which is similar to FIG. 9, and which shows themembers in another position,

FIG. 1l is an axial cross-section of another form of embodiment takenalong the line XI-XI of FIG. 15,

FIG. 12 shows on a larger scale a detail of FIG. 11,

FIGS. 13 and 14 are cross-sections taken respectively along the linesXIII- XIII and XIV-XIV of FIG. 12,

FIG. 15 is al plan view which corresponds to FIG. 11,

FIG. 16 is a view which is similar to FIG. l5 and which shows themembers in another position, and

FIG. 17 is an electric circuit diagram of an installation for thecontrol of a series of tensioning devices in accordance with theinvention which arel mounted on a textile machine.

The thread-tensioning device which is illustrated in FIG. 1 comprises abox 1 inside which are mounted two vertical co-axial shafts, namely: aninternal shaft 2 and an external tubular shaft 3 which supportrespectively at the top extremities of the said shafts a bracket 4 whichcarries'two tension cylinders 5, 6 and an arm 7 which carries tworollers, namely, a feeler roller 8 and guide roller 9 (see also FIG. 2).

The two tension cylinders and 6 have their axes parallel to the shaft 2and are rigidly yfixed to the bracket 4, that is to say, the saidtension cylinders do not rotate about their own axes. The two rollers 8and 9 are grooved rollers which are, on the contrary, mounted forrotation on shafts 11 and 12 which are respectively fixed on the twoextremities of the arm 7. The said arm is fixed on the tubular shaft 3by means of a clamping screw 14 which -passes through a hub 15, the saidhub being integral with the said arm.

The thread 20, the tension of which it is desired to adjust, passes inthe direction of the arrow f1, first over the input guide roller 8, thenover the two tension cylinders 5 and 6 so as to form an S and lastlyover the output guide roller 9.

The pivotal arm A7 which carries the feeler rollers and the bracket 4which carries the tension cylinders are coupled for rotation by means ofa step-up system which comprises an internally toothed ring gear 22 andan externally toothed wheel 23 which are respectively secured to thetubular shaft 3 which carries the rollers and to the internal shaft 2which carries the tension cylinders, whilst the internally-toothed ringgear 22 and the externally toothed wheel 23 are both in mesh with anintermediate toothed wheel 24 which is mounted to rotate freely on a pin25 which is rigidly secured in the bottom of the box 1. The pitchdiameter of the ring gear 22 is, in this example, substantially doublethe diameter of the toothed wheel 23, with the result that the angulardisplacement of the bracket which carries the tension cylinders isapproximately double the angular displacement of the pivotal arm whichcarries the feeler rollers, and takes place in the opposite direction.

The pivotal arm 7 which carries the feeler rollers is induced to performa pivotal movement in the direction of the arrow f2 (as shown in FIG. 2)and, in consequence, the bracket which supports the tension cylinders isinduced to rotate in the opposite direction with an amplitude and anagular speed which are double, under the action of a device which, inthis example,is of the electromagnetic type comprising a rotor which isgenerally designated by the reference 28, and a stator which isgenerally designated by the reference 29.

The -rotor 28 which is mounted on the tubular shaft 3 comprises two polepieces 31, 32 which are intended to co-operate respectively with twopole pieces 33, 34 of the stator. In order that the total reluctance ofthe airgap between the stator and the rotor should rem-ain substantiallyconstant, there has -been given to the two pole pieces of the stator asuitable angular displacement which is different from that of the polepieces of the rotor.l In this manner, when one of the two air-gapsdecreases in area, the other air-gap increases, thereby making itpossible to retain a substantially constant torque, 'while steps aretaken to ensure that the two oppositely facing pole pieces, for examplethe pole piece 31 of the rotor and the pole piece 33 of the stator bothhave like poles, for example north-seeking or positive poles, whereasthe two opposite faces of the two other pole pieces 32 and 34 haveunlike poles, in order to ensure that two pole pieces repel each otherwhile the other two -pole pieces attract each other and that theircombined action should consequently be in the same direction, that is tosay, in the example, the direction of the arrow f2.

There has been diagrammatically illustrated in FIG. 1 the electriccircuit for the excitation of the pole pieces of the rotor and of thestator. The electric current flows into the box 1 through a supply lead41 and passes successively through the coil 42 of the pole piece 33 ofthe stator, through a brush 43 which is secured to the box cover l0 bymeans of an insulating member 44, through the brush-contact 43 to acollecting-ring 45 which is mounted on an insulating tube 46 fixed onthe tubular shaft 3, through a supply lead 47, through the coil 48 ofthe pole piece 31 of the rotor, the coil 49 of the pole piece 32 of therotor, through another collecting-ring 51, a brush 52, and through thecoil 53 of the pole piece 34 of the stator, whereupon the currentfinally passes out of the box through a lead 54.

The operation of the device takes place as follows:

It is assumed that the apparatus is at present in stable condition ofoperation. Accordingly, the thread 20 has a tension which balances thepressure with which the feeler and guide rollers 8 and 9 as well as thetension cylinders 5 and 6 are applied against the thread under theaction of the constant torque provided by the electromagnetic device.

If for any reason the tension of the thread shows a tendency todecrease, for example, the lpivotal arm 7 which carriesthe feelerrollers will pivot in the direction of the arrow f2 under the action ofthe predominant torque of the electromagnetic device, with the resultthat the tension cylinders 5 and 6 will pivot together in the directionopposite to the arrow f2 and that consequently, the arc over which thethread is wound onto the' said tension cylinder-s will increase; thisresults in an increase in the tension'of the thread, which tends tocause the feeler rollers 8 and 9 to move back to the same extent as theyhad moved forward under the 4action of the pre dominant driving torqueof the electromagnetic device.

In the contrary case, that is to say if the tension of the thread tendedto increase, the feeler rollers would be thrust back in the directionopposite to the arrow f2, with the result that the tension cylinderswould perform a pivotal movement in the direction of the said arrowwhile producing a decrease in the length of the are over which thethread rubs against the said cylinders, which would have the effect ofreducing the tension of the thread and of initiating the return of thepivotal systems to their po sition of stable operation.

In FIG. 2, there have been illustrated the moving systems in a meanposition in which it is effective and, in FIG. 5, in a position whichcorresponds to the maximum tension of the thread in which the device isnot effective until the tension produced by the delivering and receivingl machines is reduced.

The multiplication of the amplitude of the movement and of the speed ofthe feel-er rollers with respect to the tension cylinders provides theapparatus with great sensitivity, a small response time and rapidcompensation of variations' in tension for small angular displacementsof the feeler rollers, thereby preventing troublesome timeylags andconsiderably increasing the range of adjustment provided by theapparatus.

In order to regulate the thread tension to the desired Value, it ismerely necessary to regulate the current intensity in theelectromagnetic device to the value which corresponds to the torquewhich is necessary for the pur- -pose of applying the feeler rollersagainst the thread with the corresponding pressure.

The form of embodiment which is illustrated in FIGS. 6 and 7 resemblesthe form of embodiment of FIGS. l to 5 and the same members have beendesignated by the same reference numerals; it essentially differs onlyin the fact that the stepup gear device, instead of being con stitutedby straight-tooth gears, is constituted by beve1- gears.

The arm 7 which carries the feeler rollers is mare integral with abevel-gear 61 which is secured to shaft 2 and in mesh with anintermediate bevcl-gar 62 which is mounted to rotate freely on a shaft63, the said shaft being carried by a support 64 which is mounted on the`cover of the box, the said bevel-gear 62 being in t-urn engaged'at thesame time with a bevel pinion 66, the pitch diameter of which issubstantially one half the pitch diameter of the bevel-gear 61. In thisform of embodiment, the bevel pinion 66 is provided with a collar 67 inwhich are directly mounted the two tension cylinders 5, 6. The saidpinion and its collar rotate freely on the shaft 2 which in this case,is directly coupled to the rotor 28 and is journalled in the box casingand box cover, the tubular shaft of the previous form of embodimentbeing no longer provided in this alternative form.

A casing 68 protects the reduction gear unit.

The said device obviously operates in the same manner as the devicewhich is described with reference to FIGS. 1 to 5.

The form of embodiment which is illustrated in FIGS. 8 to l() alsodiffers from the form of embodiment of FIGS. 1 to 5 solely in thestructure of the step-up gear device which, instead of being in the formof gears, is designed in the form of levers which are pivotally coupledto each other.

' The internal shaft 2 which carries the tension cylinders at the topextremity thereof is rigidly fixed at the bottom extremity thereof to acrank-pin 71 whilst the bottom extremity of the tubular shaft 3 whichcarries the feeler rollers is tted with a crank-pin 72 havingsubstantially the same length as that of the crank-pin 71, the twocrank-pins being substantially diametrically opposite in the centralposition of adjustment of the device. The stud 73 of the crank-pin 71 isengaged inside an elongated slot 74 which is formed in the freeextremity of a lever 75 (see also FIGS. 9 and l0) which pivots at theother extremity thereof about a pin 76 which is made integral with thebottom of the box 1. The stud 78 of the crankypin 72 is housed in asimilar manner inside as elongated slot 79 which is formed in the lever75 at a distance from the pin 76 which is substantially equal to onehalf the distance between the elongated slot 74 and the said pin.

Accordingly, any angular displacement of the intermediate lever 75corresponds to an angular displacement of the crank-pin 71 which issubstantially equal to double the angular displacement of the crank-pin72. The same effort-multiplication ratio is thus found between thepivotal arm which carries the feeler rollers and the bracket whichcarries the tension cylinders as in the forms of lembodiment which havebeen described in the foregoing. For constructional reasons, provisionhas stead of being designed in the form of two tension cyl` inders, isdesigned in the form of two` discs 91, 92 which are applied elasticallyone against the other with a pres- ,sure whichcan be regulated.

Further reference will not be made to the method of assembly of thefeeler rollers or to the manner in which these latter 4are urged againstthe thread as a result of the torque which is produced by theelectromagnetic system. The bottom thread-tensioning disc 91 is ttedfreely on .an internal shaft 93 which is mounted inside the tubu- A larshaft 3 which carries the feeler rollers. i A locking-pin i 94 passesthrough the bottom extremity of the internal shaft 93, the extremitiesof the said locking-pin being Y.

adapted to slide in two longitudinal slots 95, 96 formed in a socket 97provided with a cylindrical extendedl por tion 98 which is force-fittedin a hole 99 formed in the base of the box 1. The internal shaft 93 cantherefore slide vertically but cannot rotate about :its own axis.

The top extremity of the shaft 93 is threaded and is fitted with aknurled regulating knob 101 by means of which it is possible to compressto a greater or lesser extent a spring 102, one end of which is'appliedagainst the bottom end of the said knob whilst the other end of thespring is applied against a washer 103 which bears onA the upper face ofthe top disc 92 provided for the purpose of regulating the threadtension.

The end annular face of the bottom extremity of the tubular shaft 3 iscut in the shape of a cam 105 in such `manner that, when the said shaftis caused to perform The thread 20, the tension of which it is desiredtoI regulate, is guided between the two feeler rollers andy tightly`held between the two discs 91, 92.

The operation of this device is similar to` that of those forms ofembodiment which have been described above and differs therefrom solelyin the fact that the increase in tension of the thread, instead oftaking place under' the effect of an increase in the length of thearcover which the thread is wound onto the tension cylinders,

is obtained as a result of an increase in the pressure applied by thetwo discs 91, 92 under the action of the downward movement of the shaft93 which produces a slightlyl greater compression of the spring 102which applies the top disc against the bottom disc.

The said downward movement of the shaft corresponds to a pivotalmovement of the system of feeler rollersin the direction of the arrow f2(as shown in FIG. 15), which in turn corresponds to a tendency towardsinitial reduction in thread tension. thread tension will accordingly becompensated by a corresponding increase which is in turn due to the imcrease in the clamping pressure of the two discs.

As the knurled knob 101 is screwed down further on the top .portion ofthe apparatus, so the pressure of the spring is increased and thetension of the thread is consequently also increased und'er stableoperating conditions.

FIG. 16 shows the, relative position of the members i in the case of asubstantially maximum tension setting.

The devices such as have been described above in var- The said reductionin ions forms are very well suited to the adjustment, as effected bothsimultaneously and from a distance, of the tension of the threads in allthe sections of a textile machine suoli as, for example, amultiple-spindle machine, either as a function of time 'or in compliancewith any desired law. It accordingly follows, for example, that in FIG.17, there have been shown a certain number ot devices 111vforregulating-the thread tension which are titte'd with a controlelectromagnetic system of the same type as that which has been describedabove, for example, all such systems being fed in parallel from anelectric circuit comprising the following essential elements: a powerline 112 supplying alternating current, a general switch 113, fuse units114, a transformer 115, a rectifier 116, an initial-setting rheostat 117and a rheostat 118 for the automatic adjustment of the thread tension inresponse to a system 121 which is connected to a unit 122, thedisplacements of which are dependent on the diameter of cach bobbin ofthread which is undergoing formation. ln this manner, the adjustment ofthread tension is effected simultaneously on all the spindles as aAfunction of the diameter of the bobbin which is undergoing formation.

It accordingly follows, for example, that, although two feeler rollershave been illustrated in the drawings, especially for reasons ofsymmetry and primarily of balancing, it would be suflicient to provideone roller only at the output end.

It will be understood that the rheostat 118 can be replaced by any otherdevice by means of which the terminal voltage can be varied, the saiddevice being inserted, for example, in the alternating current circuitbefore the rectifier 1,16, and consisting of a transformer ormultiple-tapping autotransformer, variable-core inductance and,generally speaking, any means which makes it possible to produce actionon the current intensity simul Y taneously in all the apparatuses whichare in service on one machine or on a part of one machine.

By way of example, the following numerical data can be given in the caseof an apparatus which is constructed for a winding machine:

min.

dev-ice (this latter being located in lthe mean opening position): 8/100 sec.

Diameter of the tension cylinders: 9 mm.

Angle of total displacement of the feeler rollers: 45.

Angle of total displacement of the tension cylinders: 90.

Supplemental length of thread gripped between arms in the closedposition of the tension cylinders as comparyed with the open position ofthe tension cylinders: 40 o.

Thread employed for test purposes: Cotton, Nm 28/2,

twisted to 500 turns per metre.

When the tensioning device comprises a control system consisting of aninput feeler member and an output feeler member, it is advantageous inthe case of certain applications which can concern, for example, the useof reeling machines, winding machines, spoolers, etc., to make theelastic means which act upon the tensioning device dependent not upon aconstant torque but on a decreasing torque. In other words, if thetension of the Vwhich can be common to all thread on the input feelermember were to decrease,

member and thus producinga'preponderance of the saidactuating means, theresulting effect of which is an angular displacement of the controlsystem, the driving torque applied on the control system would tinallydecrease as a function of the said angular displacement.

There has been given in the foregoing description an explanation of themanner in which the said displacement produces action on thetension-regulating system so that the tension of the thread at theoutput end does not undergo any decrease in spite of the reduction intension at the input end.

This variation yin the value of. the driving torque of the apparatus asa function of the amplitude of angular displacement of the tensioningdevice is determined in such manner that, in any position of the controlsystem, the driving torque balances the sum of tensions both at theinput and output end, whilst the output tension is mainu tainedsubstantially constant.

Depending on the nature of the variations in the tension to becontrolled and compensated, namely, frequency, amplitude, speed of thethread considered, or depending also on the characteristics of thethreads employed, namely, the nature, size, elasticity, fragility,twist, etc., or finally according to whether the thread, the tension ofwhich it is desired to control, is delivered freely or by means ofadelivery roll, or through a false-twist spindle or at the output of adevice fitted with tins or rings or of a single-twist or double-twistspindle, etc., the etectiveness of compensation and the stability of thetension of the thread at the output end of the apparatus are obtainedeither by making use of a constant driving torque or a decreasingdriving torque.

Furthermore, it can be found that, on a same machine, an optimumtension-setting of the threads is obtained in certain cases by means ofconstant-torque tensioning devices, and in other cases by means oftensioning devices in which the torque decreases in time and alsodecreases according to the angular displacement of the control system.The apparatus in accordance with the invention is designed to carry outall these functions at will.

Moreover, the ratio of decrease in torque as a function of the positionof the tensioning device can be remotecontrolled by means of anadjustment unit or regulator the tensioning devices of a machine.

This adjustment can be either manual or automatic, and can, for examplecorrespond to a pre-arranged programme in which the return to constanttorque at any given moment can be both directed and obtained.

This range of possibilities is given to the apparatus by the operationof a variable shunt which branches the internal electric circuit of theconstant-torque electromagnetic control in such manner that the currentintensity can decrease in "those coils in` whichthe pole Y pieces repeleach other while the intensity increases in those coils in which thepole pieces attract each other. The said shunt is represented in brokenlines in FIG. 17.

A single rheostat 123 can,.for example, carry out this function for thecombined assembly of tensioning devices which are mounted on onemachine.

On the tensioning device itself, a third lead terminal at 124 (as shownin FIG. 1) is alone suicient to endow the apparatus with thispossibility of instantaneous modifcation of the nature of the drivingtorque, namely either constant torque or decreasing torque.

On the basis of the above data, it will be understood that theadjustment of the tension of the threads on either one or a number ofmachines can comply with any law of constancy or of variation.

The association of a number of tensioning devices of the presentinvention, the same applying in the case assiste controlling the feelersystem.

It will naturally be understood that `the invention is not limited tothose forms of embodiment which have been described and illustrated andwhich have been given solely by way of example, and that numerouslmodifications can be made therein without consequently departing eitherfrom the scope or the spirit of the invention.

What I claim is:

1. A thread tensioning device comprising supporting means; a feelerelement mounted on said supporting means for turning movement andadapted to engage a thread; a thread tensioning element movably mountedon said supporting means and adapted to engage the thread for increasingor decreasing the tension of the same; transmission means connectingsaid feeler element with said thread tensioning element so that saidthread tensioning element and said feeler element move opposite to eachother for increasing or decreasing the tension of the thread; torquecreating means including a stationarily mounted member and a turnablemember, said members being mechanically unconnected for torquetransmission, and electromagnetic means creating between said stationaryand said turnable member an electromagnetic torque the force of which isindependent of the position of said turnable member, said turnablemember being connected to one of said elements for urging the sameagainst the thread at a torque which is independent of the position ofsaid elements, whereby both said elements exert a selected torque on thethread irrespective of the relative position of said elements and of thetension of the thread.

2, A thread tensioning device comprising supporting means; a feelerelement mounted on said supporting means for turning movement andadapted to engage a thread; a thread tensioning element movably mountedon said supporting means and adapted to engaged the thread forincreasing or decreasing 'the tension of the same; transmission meansconnecting said feeler element with said thread tensioning element sothat said thread tensioning element' and said feeler element moveopposite to each other for increasing or decreasing the tension of thethread. said transmission means turning said thread tensioning elementat a different speed than said feeler element; torque creating meansincluding a stationarily mounted `member and a turnable member, saidmembers being mechanically unconnected for torque transmission, andelectromagnetic means creating between said stationary and said turnablemember an electromagnetic torque the force of which is independent ofthe position of said turnable member, said turnable member beingconnected to one of said elements for urging the same against the threadat a torque which4 is independent of the position of said elements,whereby both said elements exert a selected torque on the threadirrespective of the relative position of said elements and of thetension of the thread.

3. A thread tensioning device comprising a casing; a feeler; a supportfor said feeler turnably mounted on said casing for causing engagementof a thread by said feeler; torque creating means mounted in said casingand including a stationarily mounted member and a turnable member, saidmembers being mechanically unconnected for torque transmission,andelectromagnetic means creating between said stationary and saidturnable member an electromagnetic torque the force of which isindependent of the position of said turnable member, said turnablemember being connected to said support for urging said feeler againstthe thread at a torque which is independent of the position of saidelements, whereby both said elements'exert a selected torque on thethread irrespective of the relative position of said elements and of thetension of :the thread; thread tensioning means en gaging the thread andmovably mounted on said casing to increase or decrease the tension ofthe thread; and transmission means operatively connecting said supportwith said thread tensioning means for increasing the tension of thethread as saidlfeeler element is moved by said torque creating meansagainst the action of the' decreasing thread tension or is moved back bythe thread when the thread tension increases to such extent as to`overcome the constant torque of said torque creating means.

' 4. A thread tensioning device comprising a casing; a feeler; a supportfor said feeler turnably mounted on said casing for causing engagementof a4 thread by said feeler; torque creating means mounted in saidcasing and including a stationarily mounted member and a tumable member,said members being mechanically unconnected for torque transmission, andelectromagnetic means cre'- ating between said stationary and saidturnable member an electromagnetic torque the force of which isindependent-of the position of said turnable member, said turnablemember being connected to said support for urging said feeler againstthe thread at a torque which is independent of the position of saidelements, whereby both said elements exert a selected torque on thethread irrespective of the relative position of said elements and of thetension of the thread; thread tensioning means including a carriermounted on said casing for turning movement about the turning axis ofsaid support arm, and a pair of tension cylinders having parallel axesparallel to said turning axis, said tension cylinders engaging thethread to increase or decrease the tension of the thread; andtransmission means operatively connecting said support with said threadtensioning means for increasing the tension of the thread as said feeleris moved by said torque creating means against the action of the threadtension when said thread tension decreases to such an extent as to beovercome by the constant torque of said torque creating means or todecrease the tension of the thread when the feeler is moved back by thethread when the thread tension increases to such extent as to overcomethe constant torque of said torque creating. means..

5. A thread tensioning device as set forth in claim 4 wherein saidsupport includes an arm having said4 slots spaced ditferent distancesfrom the pivot axis of the intermediate lever and respectively receivingsaid pins whereby said thread tensioning means and said support` vandfeeler move at different selected angular speeds.

7. A thread tensioning device comprising a casing; a feeler; a supportfor said feeler turnably mounted on. said casing for causingengagementof a thread by said feeler; torque creating means mounted in said casingand rincluding a stationarily mounted member and a turnable member, saidmembers being mechanicallly unconnected f for torque transmission, andelectromagnetic means creating between said stationary and said turnablemember an electromagnetic torque the force of which is independent ofthe position of said turnable member, said turnable member beingconnected to said support for urging said feeler against the thread at atorque which is independent of the position of said elements, wherebyboth said elements exert a selected torque on the thread lmovementtoward andl away from the other disc; and

transmission .means operatively connecting said support with said onedisc for moving the same toward said other disc for increasing thetension ofthe thread as said feeler is moved by said torque creatingmeans against the action of the thread tension when said thread tensiondecreases to such an extent as to be overcome by the constant torque ofsaid torque creating means or to decrease the tension of the thread whenthe feeler is moved back by the thread when the thread tension increasesto such extent as to overcome the constant torque of said torquecreating means.

8. A thread tensioning device as set forth in claim 7 wherein saidsupport includes an arm having said feeler at one end, and a tubularshaft secured to said arm and mounted in said casing for turningmovement, said other disc'being secured to said tubularshaft, an innershaft located in said tubular shaft for axial and turning movement,means mounting said inner shaft on said casing nonrotatably and axiallymovable; wherein said spring means is a helical spring surrounding saidinner shaft and abutting said one disc; a projection on said inner shafton which said spring abuts; and wherein said transmission means includescooperating camming means on said tubular shaft and on said inner shaft,respectively, for moving said inner shaft and said one t 12 disc againstthe action of said helical spring when said tubular shaft is turned.

.9. A thread tensioning device as set forth in claim 3 wherein saidtorque creating means'includes a rotor having two diametrically arrangedrotor pole piecesextending the same angular distance, and a statorhaving two stator pole pieces each of which extends the same angulardistance as said pole pieces of said rotor, said stator pole piecesbeing angularly spaced an angle equal to less the angular extent of anyone pole piece, one of said rotor pole pieces cooperating with a statorpole piece of like polarity while the other rotor pole pececooperateswith a stator pole piece of opposite polarity.

References Cited by the Examiner UNITED STATES PATENTS 1,459,332 6/ 1923Hineline 242-154 2,326,714 8/ 1943 Whalton 242-154 2,554,493 5/1951Heizer 242-150 2,685,417 8/ 1954 Bartelson 242-154 X 2,833,491 5/ 1958Carroll 242-154 FOREIGN PATENTS 915,401 7 1946 France.

22,908 1 1/ 1900 Switzerland.

MERVIN STE-IN, Primary Examiner. RUSSELL C. MADER,-Exwniner.

S. N. GlLREATH, Assistant Examiner.

1. A THREAD TENSIONING DEVICE COMPRISING SUPPORTING MEANS; A FEELERELEMENT MOUNTED ON SAID SUPPORTING MEANS FOR TURNING MOVEMENT ANDADAPTED TO ENGAGE A THREAD; A THREAD TENSIONING ELEMENT MOVABLY MOUNTEDON SAID SUPPORTING MEANS AND ADAPTED TO ENGAGE THE THREAD FOR INCREASINGOR DECREASING THE TENSION OF THE SAME; TRANSMISSION MEANS CONNECTINGSAID FEELER ELEMENT WITH SAID THREAD TENSIONING ELEMENT SO THAT SAIDTHREAD TENSIONING ELEMENT AND SAID FEELER ELEMENT MOVE OPPOSITE TO EACHOTHER FOR INCREASING OR DECREASING THE TENSION OF THE THREAD; TORQUECREATING MEANS INCLUDING A STATIONARILY MOUNTED MEMBER AND A TURNABLEMEMBER, SAID MEMBERS BEING MECHANICALLY UNCONNECTED FOR TORQUETRANSMISSION, AND ELECTROMAGNETIC MEANS CREATING BETWWEN SAID STATIONAYAND SAID TURNABLE MEMBER AND ELECTROMAGNETIC